Structure elucidation and anti-tumor activity in vivo of a polysaccharide from spores of Ganoderma lucidum (Fr.) Karst

To explore new anti-tumor constituents in the fungi, a water-soluble polysaccharide, WGLP was obtained from spores of Ganoderma lucidum (Fr.) Karst. The average molecular weight of this polysaccharide was estimated to be 1.5 × 104 Da. Monosaccharide composition analysis indicated that it was composed solely of glucose. From methylation analysis, 1H and 13C NMR spectroscopy, and periodate oxidation and Smith degradation, it could be concluded that WGLP contained β-d-glucose residue exclusively, with an average repeating unit of hexasaccharide, having a backbone consisting of (1 → 3)-β-d-glucopyranosyl residues, to which the side chain consisting of terminal and (1 → 6)-β-d-glucopyranosyl residue is attached at position O-6 of the branching residues. Anti-tumor activity assays in vivo showed that WGLP could significantly inhibit the S180 tumor growth in the mice. Furthermore, no drug-related toxic reactions were observed. It was suggested that WGLP might be a potential anti-tumor agent used in the clinic.